Solar heater for water

[Scots_Charles_River]

Interesting simple invention.

The flat-pack water heater that fights climate change

A simple water heater powered just by the Sun is being tried out in Africa.

www.bbc.co.uk

 

[TLM]

An even cheaper and simpler solution: a black water bag. (Actually sold as a trekker warm shower.)

Flat plate (or coil) collectors work very well up to about 50C, which also happens to be a good temp for various bacteria to multiply. To get higher like the 60C recommended here one needs concentrating collectors, which tend to be expensive. 30 years ago when I planned a set of sun collectors at the cottage I did some calculations and the result was 2/3 flat and 1/3 concentrating to top up the temp. Never did build that though when I realized (dumb me did not think that at the beginning) that the fairly expensive thingaboob would only work for about 6 months a year here. The pay back time would be eons.

As far as I understand solar thermal collectors work very well at the Med, where one sees more than a few of them.

 

[grizzlyj]

I would think water in a clear plastic bottle in Africa would get really quite warm

 

[Jared]

Reminded of Cody's Lab video, though not heating water but trying to grow calories.

 

[cbrdave]

I remember being on a building site many years ago, there was a heavy duty black hose supplying water to the site, kettle blew up and the foreman made tea from the hose, it was in the sun for about an hour and the water was seriously hot, gave me the idea of using black soil pipe with caps either end, a fill cap and a tap on the end cap, mounted it on van, added a length of hose and used it to wash up at end of day and hose down muddy work gear,
Sold it to a mate who loved camping and he used it as a shower.

 

[Mesquite]

I would think water in a clear plastic bottle in Africa would get really quite warm

Not as quickly or as hot as a black bottle would

 

[grizzlyj]

Not as quickly or as hot as a black bottle would

That is very true but doesn't also sterilisation happen on cleanish water from the UV in a usably short time with a clear plastic bottle, maybe between the Tropics at least? Africa has a very large quantity of clear plastic bottles already

 

[Robson Valley]

There are many different kinds of clear plastics. Most of them, you will find that they block solar UV. I would never rely on it.

Municipal water supply to my house is underground. It was a measured +6C the last time I checked. That is one serious cold drink. I've never taken a thermometer into the shower with me but my curiosity is up now.

I have seen an enormous coil of big black plastic pipe on a house roof. I wonder what the stagnant temperature might be in that pipe. Even flowing gently, it must be an effective heater.

In case you're curious, the coldest I have measured here was -36C. The highest shade air summer temperature was +46C. I gasp to think what that afternoon was, out in the direct sun.

 

[grizzlyj]

I was wondering if you left a clear plastic bottle full of water in the sun near the equator would it be UV (if transmissable) or past 60 odd degrees that works first?!

 

[grizzlyj]

SODIS

https://www.cdc.gov/safewater/publications_pages/options-sodis.pdf

English training info pages;

SODIS: Training material

www.sodis.ch

"PET (Polyethylene terephthalate) is an inert plastic material that is
widely used for food packaging. ‘Plastic’ bottles used for water and
soda are almost exclusively made of PET. Only a small fraction of the
widely available transparent ‘plastic’ bottles are made of other mate-
rials, such as PVC, and these bottles are mostly used for liquids such
as edible oil rather than for water and soft drinks. PET bottles are la-
belled with the symbol “1”, though this label is sometimes missing
on bottles of local brands of bottled water. PVC (Symbol 3) can be dis-
tinguished from PET Bottles through a flame test: PET burns more
easily and produces a sweet smoke, while the smoke of PVC is pun-
gent. Bottles made of polycarbonate (PC: a durable sturdy plastic typ-
ically used for feeding milk bottles, Symbol 7) must not be used for
SODIS because they potentially release BPA, a carcinogenic com-
pound not found in PET"

"The transmittance of PET for UV-A radiation is relatively high......"

 

[swyn]

My Tasmanian bush shower water was heated by black micro bore irrigation pipe laid out in an 8’ x 4’ box with a glass lid.
Gravity fed. You went up a ladder onto the roof with a bucket of dam water, poured this into a 100 litre juice container and then went below turned on the tap and had a shower. Temperature control was by rolling a piece of carpet over the glass.
If I’d had known more about TMV’s at that time I would have fitted one which would have automatically mixed cold with the hot for that perfect temperature!
Worked well in the summer.
S